A method and apparatus for an interface switch having an external terminal electrically connected to an AC voltage Ē at a frequency ω0 (for example a utility supply), and an internal terminal electrically connected to an AC voltage V at a selectable frequency ω (for example a microsource). In one...http://www.google.es/patents/US7521825?utm_source=gb-gplus-sharePatente US7521825 - Interface switch for distributed energy resources
